Recently, it has been proposed to use, as frame bodies for protecting and packaging an electric or electronic equipment product effectively when the articles are packed in a case or cushioning members for packaging, a recyclable sheet such as a pasteboard or a corrugated cardboard instead of a plastic foam body such as styrene foam.
One frame body or cushioning member is a corrugated cardboard block formed by zigzag folding of the sheet.
Another frame body or cushioning member using corrugated cardboard or the pasteboard is, for example, as disclosed in Japanese Utility Model Application laid-open No.60-32274, a hollow block with a pseudo-honeycomb section formed by repeatedly folding a sheet at a predetermined interval and bonding or connecting necessary folds (folded parts) to each other.
In manufacturing the above-mentioned frame bodies or cushioning members, at first, the sheet member such as the pasteboard or the corrugated cardboard is cut according to the design and folding ruled lines are formed orthogonal to the longitudinal dimension of the sheet with press lines by a press, perforated lines, intermittent cutting lines or the like according to the design.
Next, the sheet is folded along the above-mentioned ruled lines so that the ridge-like folds and the valley-like folds are formed alternately and then necessary portions are pasted to each other to make a block of a desired shape.
The frame bodies or cushioning members should be manufactured to have an accurate shape and size, since, as previously mentioned, they are used for supporting articles properly and protecting the articles from impact in circulation and for packaging the articles easily and efficiently.
It is difficult to manufacture the product of an accurate shape and size because the folded part tends to shift easily when the sheet, formed as above-mentioned, is folded by industrial means along the folding ruled lines. In order to fold the sheet along the folding ruled lines accurately and industrially, it is preferable to give directional permanency of folding (folding habit) to the folding ruled lines of the sheet.
However, no industrial means for imparting accurate directional permanency of folding to the sheet along many folding ruled lines formed in the sheet has been developed (it has been conducted by handwork). Therefore, the frame bodies or cushioning members of plastic foam have not been yet replaced by those using the sheet of a pasteboard, a corrugated cardboard or other recyclable materials.